Domsarto did a lot of junctions a while ago, they are UK road markings but you could always edit the textures (for your own use). TLanders has put a good few roads on the DLS recently, maybe he plans to do something like this.
Personally (especially if it's for an urban area) I use Andi06 "traffic" assets (basically "Traffic activated" road markings with no road) and place these on top of a textured baseboard or a "no traffic" road type spline asset. These give you a lot of flexibility.